The present invention relates to an extract obtained from the herb of plants belonging to the genus Epimedium sp. of the family Berberidaceae, a process for preparation of this extract, an antibacterial agent comprising this extract as an effective component, and an antibacterial therapy by using this extract.
As the plant belonging to the genus Epimedium sp., there are known Epimedium macranthum, M. et. D, var, violaceum, Fr., Epimedium sagittatum, Bak., Epimedium macranthum, M. et. D., Epimedium koreanum, Nak., etc. These plants are perennial herbs growing naturally in Japan, China and Korea, etc. The stalks, leaves and roots are called "Inyokaku" in the field of Chinese medicines. The herb of such plant is infused and used as a cordial or tonic medicine. The effect is not substantially different among species of plants belonging to the genus Epimedium sp. A single species or a mixture of two or more of species is marketed as a crude drug called "Barrenwort". Components of this Barrenwort have been studied from old and reports have been published, for example, by: Akai et al., Yakugaku Zasshi, 55, 537, 705, 719, 788 and 1139 (1935); Tomita et al., Yakugaku Zasshi, 77, 114 and 212 (1957), Maeda, Tohio Izi Sinsi, No. 2133 and 2795 (1932); Miyake, Okayama Igakkai Zasshi, 49, (10) and 2043 (1937); and Hirashima et al., Clinical Report, 4, 139 (1970). But their details are still unclear in many points.
We have conducted research on this Barrenwort and found that an extract obtained by extracting plants belonging to the genus Epimedium sp. with a mixed solvent of water and a water-miscible organic solvent or with water and collecting a high-molecular compounds-containing fraction from the obtained aqueous extract has an excellent antibacterial activity. We have now completed the present invention based on this finding.